Flow control valves are well known in irrigation systems. They control the flow of water through an upstream pipe and thereby turn sprinklers fed by the pipe on and off. Such valves are often remotely controlled by control signals sent from an automated irrigation controller. For example, the controller often sends an electric actuating signal to a solenoid that is part of the valve to open the valve.
Some irrigation valves also include a "manual on" feature that involves manually manipulating the solenoid relative to the valve housing. An actuator arm sticks out beneath the solenoid. The user can grip and rotate this arm to partially unscrew the fitting in which the solenoid is received. This manually opens the valve. The actuator arm can be rotated back to its original position to restore the solenoid to its normal operational position to close the valve.
This type of actuator arm used to effect a "manual on" operation of the valve can be difficult to find and grip. It is horizontal and located beneath the solenoid near the top of the valve. Since the valve is itself often located within a valve box, and since the valve box is sometimes filled with water thus partially or completely submerging the valve, the actuator arm may not be visible to the user. In these circumstances, the user must reach down and find and rotate the actuator arm by feel.
Irrigation valves of this type often include a valve housing that is formed from a valve body that is closed by a bonnet. A plurality of attachment screws extend through mating surfaces in the valve body and the bonnet to join these two components together. The task of assembling the valve is made more difficult by the need to align the screw receiving holes in the bonnet with the screw receiving holes in the valve body. Moreover, it is easy to lose the attachment screws when the bonnet is disassembled from the valve body.
Finally, valves of this type often use a metering pin that extends through a metering hole in the valve member. Water passes from one side of the valve member to the other around the metering pin which is sized to be slightly smaller in diameter than the diameter of the metering hole. However, sand and other small debris can often lodge between the metering hole and the metering pin, thereby interfering with the proper operation of the valve or potentially disabling the valve. It would be desirable for the valve to be able to pass or dislodge such debris during operation of the valve and to thereby be self-cleaning.